john sasaki has the story. >> reporter: police officers and state agents dropped the hammer on some of oakland's most violent offenders. all part of an effort to rid the streets of violent offenders. >> probably the most violent group of people i've seen in the last few years. >> reporter: they're violent not for money or turf. >> it was basically they hated the other gang. >> reporter: police released this surveillance video they say was committed by members of that new gang. >> we found out fairly quickly that these groups every day were planning on ways to commit violent acts within the community of oakland. >>> this - - >> reporter: this is all part of operation seize fire. oakland city officials hosted a huge press conference with other local state and federal law enforcement which have been leading related efforts. >> there were 23 arrests and in those arrests we have seized 55 firearms that included four assault weapons. >> reporter: afterward, mayor quan told us that it was meant as a warning to those offenders. >> it's basically a warning to those people that are out of contro